The Japan Meteorological Agency is expanding its weather forecast and warning periods for the first time in 30 years [1].
This shift comes as Japan faces a record increase in disaster-level heatwaves and torrential rains, necessitating earlier disaster prevention measures to save lives and protect infrastructure.
The agency plans to extend the current one-week forecast period to a maximum of two weeks [1]. Similarly, the window for providing potential warning information will be increased from five days to two weeks [1]. These changes are driven by improvements in forecasting accuracy, which officials said have now made it possible to provide forecasts up to one month in advance [1].
Takashi Nakamura, the chair of the review committee from the University of Tokyo, said the transition is important for public safety. He said that because information for early awareness will be released simultaneously, earlier preparation will be possible, and he urged individuals and local governments to utilize these tools.
The agency will release a formal report on these changes in August 2026 [1]. Following the report, the new operational system will be implemented gradually, with full integration expected by 2030 [1].
This is the most significant overhaul of the agency's forecasting operations since 1996 [1]. The updated framework aims to bridge the gap between long-term climate trends and immediate emergency alerts, providing a critical window for municipalities to mobilize resources before extreme weather hits.
“The Japan Meteorological Agency is expanding its weather forecast and warning periods for the first time in 30 years.”
By extending the forecasting window, Japan is shifting its disaster strategy from reactive emergency response to proactive mitigation. This change acknowledges that the increasing frequency of extreme weather events requires a longer lead time for evacuation planning and resource allocation, moving beyond the traditional short-term warning cycle.
